Cardiovascular System Flashcards
What structures does the blood flow through to the heart?
Great veins (venae cavae on the right and the pulmonary vein on the left) –> Atria –> Ventricles –> Great Arteries (pulmonary artery on the right and the aorta on the left)
What are the two sets of valves on each side of the heart?
Atrioventricular and semilunar valves. They direct blood flow to the next structure and prevent backflow.
The atrioventricular valves connect the atria and ventricles. What are the two atrioventricular valves and what side of the heart are they in?
The tricuspid valve is on the right side and the bicuspid/mitral valve are on the left side
How does the pulmonary circuit work? Include details of the valves
The blood comes into the right atrium through the vena cava into the right ventricle where the tricuspid valve is which is then pushed into the pulmonary arteries in the lungs. From there they pick up oxygen in the lungs the blood travels lack to the heart through the pulmonary veins into the left atrium and then to the left ventricle (where the bicuspid/mitral valve is) and out to the body’s tissues via the aorta.
What is it called when the heart is in a contractile state?
Systole
What is it called when the heart is in a relaxed state?
Diastole
What are the 3 stages of the cycle of the heart?
Atrial Systole = Contraction of the atria
Ventricular Systole = Contraction of the ventricles
Diastole = Relaxation of both the atria and ventricles
When do the valves open or close?
Valves open when the chamber before it has a higher pressure than the chamber it’s going into; this prevents backflow due to pressure difference.
When do the atrioventricular valves open?
During atrial systole so blood can enter the ventricles
When do atrioventricular valves close?
During ventricular systole
When do the semilunar valves open?
During ventricular systole so that blood can leave the heart through the great arteries (otherwise it would re-enter the atria).
What is after-load?
How much pressure needs to be put on the blood for it to leave the system AFTER ventricular systole
What is pre-load?
The force that stretches the cardiac muscle prior to contraction BEFORE ventricular systole
What can an ECG tell us?
If someone has too high sodium or potassium. It can also look at pressure and force.
What’s the sinoatrial node (SAN)?
Pacemaker of the heart. Self-contractile but the brain can tell it whether to speed up or slow down. It’s a group of cells found high in the right atrium close to the junction in the superior vena cava. Stimulates atrial myocardium to contract.
What is the antrioventricular node (AVN)?
Receives electrical impulses from the atria and then transmits the electrical impulse from the atria to the ventricles.
What’s the Bundle of His?
Receives input from the atrioventricular node (AVN) and propagate impulses to the left and right ventricles. Each of the branches end in Purkinje Fibres.
What is Frank-Starling Law?
The more blood in the heart during systole is equal to how much blood goes back to the heart during diastole
What are the 2 cardiac volumes during the cardiac cycle? And what are they for?
Ventricular End-Systole Volume and Ventricular End-Diastic Volume
Volumes used to calculate other parameters that are indicative of cardiac function
What is ventricular end-systole volume?
Volume of blood in the ventricle after systole
What is ventricular end-diastic volume?
Volume of blood after diastolic systole
What is stroke volume?
The volume of blood ejected from the heart in one cardiac cycle
How is stroke volume calculated?
In ml
left ventricular end-diastolic volume - left ventricular end-systolic volume
What is cardiac volume?
Total volume of blood that’s pumped through the heart per minute
How is cardiac volume/output calculated?
In ml/min
Stroke volume x heart rate (beats per min)
What is the ejection fraction?
Demonstrates the % of blood the heart receives that’s ejected during systole
How is the ejection fraction calculated?
In %
Stroke volume / left ventricular end-diastolic volume
What vessels does the blood follow after going after left ventricle contraction?
Arteries (thick outer walls and small lumen) –> arterials (narrower that can be told to get dilated or constricted in response to blood pressure) –> capillaries (where they leave and perfuse the particular organs so are one-cell thick, collapse when BP drop) –> venules in the venus system (veins, have valves, have reverse pressure to suction blood to the heart).
What is total peripheral resistance (TPR)?
The amount of force that’s exerted on circulating blood by the vasculature of the body. It’s mainly determined by the arterioles of how dilated or constricted they are in response to BP.
What is mean arterial pressure (MAP)?
The driving force for blood flow and if it drops organs risk being underperfused.
How do you calculate Mean arterial Pressure (MAP)?
Co x TPR
MAP changes depending on signals from baroreceptors and RAAS system
What are the artery branches off the arch of aorta?
Brachiocephalic artery branches to the right subclavian artery and right common carotid artery
The left subclavian artery and the left common carotid artery come directly off the arch of aorta
What’s the RAAS system?
The kidney senses a drop in blood pressure the kidney releases renin which stimulates angiotensinogen and 1 is converted into angiotensin 2 by ACE from the lungs which causes vasoconstriction leading to blood pressure rises. It also activates aldosterone (in the adrenal coretex) which causes posterior pituitary to release ADH/Vasopressin which holds on to H2O and Na+ but loses K+ which results in sodium retention and therefore an increase in blood pressure.
What does the left atrium heart feed into and what percentages are these?
25% skeletal muscle, gastrointestinal and renal
15% cerebral
5% coronary and skin
